Heart rate variability levels in COVID-19 recovered patients are closely associated with the levels of IgG antibodies in plasma targeting the SARS-CoV-2 RBD protein

Background: Previous studies have established an association between heart rate variability (HRV) and physiological processes such as inflammation and immune responses. This investigation aims to determine if there is a correlation between HRV and the levels of IgG antibodies to the receptor-binding domain (RBD) of SARS-CoV-2 in individuals. Methods: This study involved 247 individuals who had recovered from COVID-19 and participated in a blood donation drive at the Central Blood Station in Liangshan, Sichuan, from March 1 to March 10, 2023. During these sessions, five-minute electrocardiograms were recorded while the donors were at rest, to analyze HRV in both time and frequency domains. The levels of IgG antibodies against the SARS-CoV-2 RBD protein were measured using the enzyme-linked immunosorbent assay (ELISA). Results: Bivariate correlation analysis illustrated that the spectral components of HRV — specifically the very low frequency power, low frequency power, and the low/high frequency ratio — are significantly inversely correlated with the levels of IgG antibodies targeting the SARS-CoV-2 RBD protein (P-values of 0.048, 0.031, and 0.076, respectively). After adjusting for confounding factors such as age and gender in a multivariate linear regression model, the very low and low frequency powers persisted as independent predictors of the IgG antibody levels against SARS-CoV-2 RBD protein (P-values of 0.024 and 0.047, respectively). Conclusions: The frequency domain indicators of HRV are independent determinants influencing the levels of IgG antibodies to the SARS-CoV-2 RBD protein. Further research is required to elucidate the underlying physiological and pathological mechanisms.